Question

4^x-5 + 4^x-3 =68

Answer 1

\(4^x-5+4^x-3=68\\ \Rightarrow4^x+4^x-5-3=68\\ \Leftrightarrow2\times4^x-5-3=68\\ \Rightarrow2\times4^x-8=68\\ 2\times4^x=68+8\\ 2\times4^x=76\\ \Rightarrow\dfrac{2\times4^x}{2}=\dfrac{76}{2}=38\\ \Leftrightarrow x=\dfrac{In\left(38\right)}{2In\left(2\right)}\)

Answer 2

\(4^{x-5}+4^{x-3}=68\)

\(\dfrac{4^x}{1024}+\dfrac{4^x}{64}=68\)

\(\dfrac{17.4^x}{1024}=68\)

\(17.4^{x-5}=68\)

\(4^{x-5}=4\)

\(x-5=1\)

\(x=6\)

Answer 3

sao bài lớp 7 đã xuất hiện ln rồi vậy?

Answer 4

`4^(x-5) +4^(x-3) =68`

`4^(x-3-2) +4^(x-3) =68`

`4^(x-3) *1/4^2 +4^(x-3)=68`

`4^(x-3) = 68 : (1/4^2 +1) =64`

`4^(x-3) = 4^3`

`=>x -3 = 3`

=>x =3+3=6`

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